Best SMTP Servers in 2025

Postfix is a mail transfer agent (MTA) that routes and delivers electronic mail.

Key Postfix features:

Security Performance Compatibility Reliability

Anything blends AI and human support to detect, delegate, and complete your tasks before they even reach your to-do list.

Key Anything.so features:

Proactive Task Detection One-Swipe Delegation Human + AI Assistant Squad

Visit website freemium €99.0 / Monthly

Zimbra is trusted by over 500 million users to increase productivity with a complete set of collaboration tools while maintaining total control over security and privacy.

Key Zimbra features:

Open Source Cost-Effective Scalability Feature-Rich

Microsoft Exchange Server is a messaging and collaborative software product developed by Microsoft.

Key Microsoft Exchange Server features:

Integration Security Scalability Mobility

A fully fledged, free email server solution, an open source project (GPL v2).

Key iRedMail features:

Open Source Comprehensive Features Easy Installation Excellent Documentation

Open Source

hMailServer is a free e-mail server for Microsoft Windows.

Key hMail Server features:

Free and Open Source Cross-Platform Compatibility Wide Protocol Support Built-in Anti-Spam and Anti-Virus

Sendmail is a general purpose internetwork email routing facility that supports many kinds of...

Key Sendmail features:

Established Reputation Highly Configurable Open Source Wide Compatibility

sSMTP is a simple MTA to deliver mail from a computer to a mail server.

Key sSMTP features:

Lightweight Easy Configuration Secure Email Sending Simplified Use Case

Axigen is an integrated email, calendaring & collaboration platform, built on a Linux mail server technology.

Key Axigen features:

Integration Capabilities Security Features Cross-Platform Support User-Friendly Interface

Exim is a message transfer agent (MTA) developed at the University of Cambridge for use on Unix systems connected to the Internet.

Key Exim features:

Highly Configurable Flexible Routing Active Community Support Efficient Transport Mechanism

Open Source

CMail is a free Windows command line mailer with advanced message formatting options.

Key CMail features:

User Interface Security Features Integration Customization

free

An open source mailserver suite.

Key mailcow features:

Comprehensive Feature Set Open Source Docker-based Deployment Active Community and Support

Open Source

OpenSMTPD is a FREE implementation of the server-side SMTP protocol as defined by RFC 5321, with...

Key OpenSMTPD features:

Simplicity Security-focused Lightweight Integration with OpenBSD

Open Source

PowerMTA is an industrial-strength software for high-volume email delivery.

Key PowerMTA features:

High Deliverability Scalability Advanced Analytics Customization